Acoustic scattering from microfibers of Parylene C

The acoustic scattering characteristics of ∼10 μm-long microfibers of Parylene C embedded in water were investigated, towards the eventual goal of designing polymeric sculptured thin films for biomedical applications. The chosen microfibers were upright circular-cylindrical, slanted circular-cylindrical, chevronic, and helical in shape. A combination of numerical and analytical techniques was adopted to examine the scattering of plane waves in a spectral regime spanning the lower few eigenfrequencies of the microfibers. Certain maximums in the spectrums of the forward and back scattering efficiencies arise from the phenomenon of creeping waves. The same phenomenon affects the total scattering efficiency in some instances. The spectrums of all efficiencies exhibit the geometric symmetry of a microfiber in relation to the direction of propagation of the incident plane wave. Similarities in the shapes of the slanted circular-cylindrical and the chevronic microfibers are reflected in the spectrums of their scattering efficiencies. A highly compliant microfiber has shorter and broader peaks than a less compliant microfiber in the spectrums of the total scattering efficiency. The proper design of polymeric sculptured thin films will benefit from the knowledge gained of the directions of maximum scattering from individual microfibers.